PROJECT SUMMARY/ABSTRACT The overall goal of the proposed K43 Emerging Global Leader Award is to support Dr. Andrew Mujugira?s research training to develop as an independent global health HIV researcher. Dr. Mujugira is currently a postdoctoral fellow at the Infectious Disease Institute in Kampala, Uganda. Conducting the proposed studies in this application will facilitate his training goals to: 1) develop a solid foundation in behavioral science; 2) gain expertise in mobile technologies for behavior monitoring and intervention; and 3) acquire qualitative data collection, analysis and writing skills. This proposal builds on the unique skills he already has in clinical trials, epidemiology and medicine while leveraging a multidisciplinary team of mentors to ultimately become a productive and influential independent investigator focused on HIV prevention in key populations. The research goal of this proposal is to conduct a rigorous proof-of-concept evaluation to test if HIV self-testing (compared to clinic-based testing) motivates PrEP uptake and adherence, and empowers effective prevention decision making in sex workers. Transgender, male, and female sex workers are 49, 21 and 14 times as likely to be HIV-infected as other adults in the general population. In Uganda, sex workers have high HIV seroprevalence (35-37%) and account for 10% of new HIV infections. Two robust, evidence-based, self-controlled HIV prevention tools are available -- HIV self-testing (HIVST) and antiretroviral pre-exposure prophylaxis (PrEP) -- but these are not currently well utilized among sex workers. HIVST and PrEP are complementary tools that could be combined to build self-efficacy and empowerment, increase PrEP adherence and reduce sexual risk behaviors. However, research is needed to show how combination HIVST and PrEP may have a synergistic impact on uptake and use of each prevention intervention. To address these questions, Dr. Mujugira will conduct a randomized trial among sex workers initiating PrEP in Uganda to test if HIV self-testing increases PrEP adherence among HIV- uninfected sex workers (Aim 1), decreases sexual risk behavior in sex workers taking PrEP (Aim 2), and influences prevention choices among sex workers and their partners (Aim 3). He will use novel technologies (real-time electronic monitoring with Wisepill technology and mobile phone surveys) to characterize patterns of PrEP adherence, and assess how use of HIVST and PrEP aligns with sexual risk behaviors. Additionally, he will conduct in-depth qualitative interviews to explore the mechanisms through which combined HIVST and PrEP delivery may be synergistic and empowering. This study will be the first to jointly evaluate HIVST and PrEP in sex workers. Dr. Mujugira?s research goals correspond with his training goals, and by the completion of this award, he will be in an excellent position to submit an R01 application that furthers the research agenda in HIV prevention.